Rust is only found on ferrous metals. But it is very often a problem there - whether in a car, motorcycle, steel structure or metal gate. How to remove existing rust, where it can no longer be removed easily, and where further measures are necessary, you can read here in detail and clearly.
Mechanical rust removal
The easiest way to remove rust is by mechanical means. You can do this with different methods:
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- Hand sanding
- Machine grinding
- Sandblasting or glass bead blasting
The mechanical methods remove visible rust on ferrous metals. The superficial layers can, however, already be altered by extensive rusting, and continue to corrode quickly despite the rust removal.
The rust removal must therefore be carried out very thoroughly, the surface layers must also be removed (except for the bare metal) and then appropriate protective treatment or the application of a rust converter should be carried out in order to avoid re-rusting and to protect the susceptible surface.
Chemical rust removal
Chemical rust removal uses strong acids. They detach the rust from the surface and react with the corroded surface layers. The rust is mostly removed by chemical methods "deep into the pores", further corrosion is often prevented.
The acids used are:
- Hydrochloric acid (€ 6.95 at Amazon *)
- Oxalic acid
- all other strong acids, such as acetic acid or citric acid
Hydrochloric acid is very aggressive and can quickly and severely weaken the surface of the ferrous metal through the entry of hydrogen. It is precisely here that it is advantageous to treat the cleaned surface with rust converter.
Oxalic acid (clover acid) or a solution of the associated clover salt, on the other hand, is a very gentle process that hardly attacks other substances and, above all, leaves paints and varnishes on the metal intact. It is therefore also used to clean older to antique finds.
Rust removal by electrolysis
Rust removal by electrolysis is another way of removing rust, especially small metal parts, very gently. The electrolysis process is based on the same laws as the active corrosion protection of metals. It just works the other way around.
The strength and speed of the rust removal process can be influenced by the choice of electrolyte and the applied current. The process is also suitable for very delicate and antique metal objects. They can be de-rusted almost completely as long as there is still an intact metal core.
With the help of phosphoric acid, rust cannot be removed, but converted. The iron oxides that make up rust are converted by the action of the phosphoric acid into stable iron phosphates that no longer corrode.
This not only creates a stable, further workable surface, but also a waterproof protective layer that prevents further corrosion at this point. It is important, however, to observe the limits of the process.
Converting the rust alone is often not effective. It is better to combine mechanical or chemical methods with rust conversion and subsequent thorough sealing.
Inactivation of rust
Various agents, including Owatrol oil and linseed oil, can stop the progress of rusting for a period of time. In the narrower sense, however, this is only an emergency measure, not a real fight against rust. Just stopping rust is not a permanent solution, it is only effective for a short period of time.
Constructive rust control
If problems such as contact corrosion or crevice corrosion arise, combating rust alone is not enough. Here, the causes, which usually lie in structural defects or the use of unsuitable materials, must be combated in advance so that a meaningful rust removal is even possible.
If the rust has eaten its way through the material, rust control is often no longer successful. Instabilities have already occurred in the material, or the rust is so deep that the material would break apart. In this case, the only thing that helps is welding in replacement material (such as sheet metal on a car) or completely replacing the respective part.Tips & Tricks When fighting rust, always be careful and work very precisely. Hidden rust nests can often cause even more damage than openly visible ones. In addition, always fight rust early on.